The present invention relates generally to die rule holders and more particularly to die rule retaining boards having incorporated therein a die rule retention device.
Steel rule dies are widely used to cut a variety of materials such as cardboard and plastics into a desired shape. Often, the steel rule dies are pressure inserted into slots located in a retaining board made of wood or other suitable material. During the operation of a cutter, the dies often become loosened and ultimately disengaged, thereby necessitating costly and time consuming interruption of the cutting process when repairs are undertaken. In addition, the slots are of varying widths to accommodate dies of varying widths, thus making standardization difficult.
Several attempts have been made to prevent this loosening of steel rule dies. For example, U.S. Pat. No. 4,052,886 discloses a solid base material having caverns which are filled with semi-rigid filler material to anchor an inserted steel die. However, this method requires time-consuming filling of the semi-rigid filler material and the ultimate strength of securing the rule is dependent on the filler material selected.
U.S. Pat. No. 3,941,038 discloses the use of S-wall shaped resilient members which pin a die rule between the resilient members and packing shims. This apparatus necessitates a difficult insertion of the rule between the resilient member and the shims.
Another proposal is shown in U.S. Pat. No. 3,835,746. A resilient support and spring are deformed upon insertion of a die into a die slot and thereafter exert an upward force against the die to secure it in a slot. Such a deformation ultimately leads to mechanical failure of the retaining system as the die is continuously displaced.
Accordingly, it is an object of the present invention to provide an apparatus which securely retains die rules in a retaining board.
It is a further object of the present invention to accomplish the foregoing object without difficult insertion of the die rule.
It is yet another object of the present invention to accomplish the proceeding objects simply and economically.
It is a still further object of the present invention to achieve the foregoing objects with an apparatus that is durable and long lasting.
It is another object of the present invention to achieve the above objects for steel rule dies of varying widths.
Other objects and advantages of the present invention will be apparent from the specification and drawings which follow.
The foregoing and additional objects are obtained by an apparatus according to the present invention for securing die rules inserted in associated die slots in a die rule retaining board. The apparatus includes at least one chamber located adjacent to each slot and having an open face opening towards the slot. The chamber is oriented substantially perpendicular to the direction of insertion of the die rule. Magnetic retention means, for example, a permanent magnet, is provided in each chamber for urging the inserted die normally towards the retention device. Accordingly, a magnetically attractable die can be securely yet removably held within the die slot upon insertion into the slot due to the magnetic attraction between the retention device and the die rule.